THE INORGANIC ELEMENTS IN NUTRITION.*

BY THOMAS B. OSBORNE AND LAFAYETTE B. MENDEL.

WITH THE COOPERATION OF EDXA 1~. FERRY AND .ILFRED J. WAKEMAN.

(Prom the Laborcctory of the Connecticut Agricultrrral Experimend Station and the She$cEd Laboratory of Physiological Chemistry in Yale

Universily, Xeut Haven.)

(Received for publication, February 15, 1918.)

It has long been recognized in a general way that the inorganic components of the diet play a &le that cannot be neglected.. UntSil rccent,ly the mineral nutrients have been largely considered i?‘~, tolo only, their content being expressed as per cent of “ash” yielded by a given food, ration, tissue, or organ. Even a casual study of the literature of nutrition impresses one with the ex- ccedingly fragmentary and indcfinitc knowledge regarding the functions of t.he in&garlic elements in the diet.

In their r&urn6 Albll and Neuberg remarked:’

“So wenig wie die wissensc.haftliche Medizin zurzeit den Salzen in der Erntihrungsphysiologie die ihnen gebtihrende Bedcutung zuerkennt, wtir- digt sie such die Rolle, welche sie in der Entstehung und Entwickelung von Ern:ihrungstiirungen und Stoffwechselanomalien spielen. Ohne die von Liebig, Voit und Forster in dieser Richtung gegebenen Anregungen weiter zu verfolgen, hat die chemische Stoffwechselforschung in den letz- ten Jahrzehntcn ihre Interesse fast ausschliesslich auf die orgnnischen NBhrstoffe konzentriert. Die unorganischen Bcstandtcile dcr Nnhrung und die Stiirungen im Umsatz derselben sind noch heute ein ziemlich brach liegendes Arbeitsfeld. Die Versuche einzelner Autorcn, die Forschung auf diesem Gebiete anzuregen, sind bisher stets so fruchtlos geblieben, dass man an der Richtigkeit des Grundgedankens ernste Zweifel hegen

* The expenses of this investigation were shared by the Connecticut Agricultural Experiment Station and the Camegic Institution of Washing- ton, D. C.

A preliminary report was presented at the Minneapolis meeting of the American Society of Biological Chemists, December, 1917.

1 Albu, A., and Ncuberg, C., Physiologie und Pathologic des Mineral- stoffwechsels, Berlin, 1910.

131

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132 Inorganic Elements in Nutrition

kijnnte, wenn man nicht wiisste, wie schwer oft Ideen FUSS fasten, welche sich nicht in der Richtung der hergehrachten Schulmeinung und der ererb- ten Tradition bewegen!!’

This paucit,y of information is made evident, for example, by two recent representative test-books,*z3 which summarize the latest concept,ions in this field of physiology. Although there is almost unanimity of opinion regarding the energy needs of the body under different circumstances of age and activity; although the current estimates of the minimum amount of protein required per day seem to he defined within reasonably narrow limits; although the funct.ions of fat and carbohydrate and the possi- bilities of their interchange are beginning to be understood; there is no adequate experiment.al basis whatever to permit tenable statements regarding either the indispensability, or the minimum requirement, of any of the inorganic constituents of the dietary wjth the possible exception of calcium and phosphorus. Statistics show enormous divergencies between the mineral intakes of peopIe in different regions; but these appear to be the fortuitous results of widely unlike dietaries including water (as is the comparative dissimilarity in the fat and carbohydrate content of the diets of peoples living respectively in a tropical or frigid climate-differ- ences enforced by the unlike character of the available food sup- plies) rather than the expression of unlike metabolic needs. A beginning has hardly been made in this field of investigation.

It is obvious that a growing, and bone-producing, or a milk- producing animal, requires calcium and phosphoric acid, and that at a.11 periods of life chlorides are essent,ial for the production of gastric juice. Conclusions like these afford an insufficient basis regarding the speci$c use of these as well as the other individual elements. Earlier observations have made it plain that stron- tium cannot replace calcium, and that Iithium compounds are t,oo toxic to be subst,it,utecl for other alkalies. Whether the al- kalies or alkali earths are to any degree interchangeable in the physiological function cannot be answered on the basis of any experimental evidence. The fetal abhyrosis which results from

2 Lusk, G., The Elements of t,he Science of Nutrition, Philadelphia, 3rd edition, 1917.

3 .Irmsby, H. P., The Nutrition of Farm Animals, New York, 1917.

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T. B. Osborne and L. B. -Mendel 133

an assumed deficiency of the usual traces of iodine in the diet is an illustration of the unquestionable importance of one of the less common elements.4

The recent conceptions of “physiologically balanced” solutions in their relation to biological phenomena, conceptions enlarged by Lo& and others, complicate the problem considerably by forcing a consideration of the possible an6agonistic actions of different ions; for in many instances physiological well-being seems to depend on a balance between stimulations and inhibitions in which the inorganic make-up of the medium may play a directive r81e. Again the modern conception of the balance of acids and bases in the body makes t,he interpretation of experiments affect- ing the inorganic metabolism of the organism difficult. Evidently it is imperative, if possible, to replace hypot,hesis and speculation by experimentally established facts.

The idcal method which at, once suggests itself for studying the role of the inorganic elements individually and collectively in nutrition would consist in observing the effect of synthetic diets in which the cont.cnt of every ingredient. could be regulat,ed at, will both as to quantity and quality. Under such conditions the requirements of plants for the various inorganic elements were long ago demon&rated; but. hitherto it. has been impossible to apply similar m&hods to animals because mixtures of purified foodst,uffs have always led to nutritive failure.

Since the demonstration5 that comparatively small additions of yeast to otherwise suitable artificial food mixtures will render them entirely adequate for gr0wt.h and maintenance, it has become possible to prepare diets from which one or another inorganic constituent can be excluded with the exception of the minute quantities introduced with the yeast and the unavoidable traces contained in the purified constituents of the foocl.

Accordingly we have prepared a large variety of salt mixtures in which one or more of the elements has been omitted and rc- placed by increments of the remaining ones so as to maintain the balance of acids and bases therein as nearly as possible. These were used to replace the complete mixture of inorganic salts which

* Smith, G. E., J. Hid. Chet~z., 1917, xxix, 215. 5 Osborne, ‘I’. B., and Mendel, 1,. B., J. Aiol. Chem., 1917, xxxi, 149.

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Inorganic Elements in Nutrition

our experiments as well as those of others have shown to be ade- quate for the support of white rats from infancy to maturity.

The various alWed salt, mixtures employed were made by dissolving the carbonates of the bases used in solutions of the required jcids and then adding traces of other elements as aque- ous solutjions of their salts. The resultant solution of the salts thus formed was then added to lactose, evaporated until the residue was dry, pulverized, and incorporated in suitable proportions in the food.

The chemicals used in these experiments were mixed in the proportions shown in Table I.

The foods had the following general composition:

Protein., ................... Lactose-snlt, mixture ........ Brewer’s yeast, dried ........ Starch ...................... Butt,er fat .................. Lard ........................

........ ........ ........ ........ ........ ........

. . .

. .

......... ......... ......... ......... ......... .........

per cent . 18.0

25.ck29.5 . 1.5- 2.0

25.5-27.5 . 18.0

7.0

The animals on these diets were given distilled water to drink. Since in using foods from which one or more of the different

inorganic ions had been int.entionally omit,ted it was impossible t,o exclude traces of t,hem occurring as impurities in the organic products used, including the yeast, a quantitative analysis was made of cnch ingredient of the various diets, and the total content of each clement’ accurately determined.

K-free food (VII) contains 0.033 per cent K.* Control food (IV) contains 0.833 per cent K.*

Mg-free food (VIII) contains 0.012 per cent Mg. Control food (IV) contains O.OSO per cent Mg.

G-free food (IS) c’ontaina 0.008 per cent Ca. ControI food (IV) con- tains 0.546 per cent Ca.

Nn-free food (X) contains 0.035 per cent Na.” Control food (IV) con- tains 0.185 per cent Na.*

Cl-free food (SIB) contains 0.035 per cent Cl. Control food (IV) con- tains 0.529 per cent Cl.

Mg-, Na-, Cl-free food (XII) contains 0.012 per cent Mg. ControI food (IV) contains 0.080 per cent Mg.

* Na 2nd I< were not determined separately in the casein.

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TABL

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T. B. Osborne and L. B. Mendel 135

Mg-, Na-, Cl-free food (XII) contams 0.035 per cent Na.* Control food (IV) contains 0.185 per cent Na.*

Mg, Nn-, Cl-free food (XII) contains 0.035 per cent Cl. Control food (IV) contains 0.529 per cent Cl.

Na-, K-free food (XIII) contains 0.035 per cent Na.* Control food (IV) contains 0.185 per cent Na.*

Na-, K-free food (XIII) contains 0.033 per cent K.* Control food (IV) contains 0.833 per cent I~.*

Ca-free, Jig-rich food (‘XV) contains 0.008 per cent Cn. Control food (IV) contains 0.546 per cent CR.

IQ-free food (SVI) contains 0.169 per cent P in casein food. Control food (IV) cont,ains 0.511 per cent P in casein food.

PO,-free food (XVI) contains 0.035 per cent P in edestin food. Control food (IV) contains 0.372 per cent P in edestin food.

According to these figures none of the food mixtures were strictly Na-free, Mg-free, et,c., but comained small, measured contaminations of the elements sought. to be excluded, which in most were insignificant, in comparison with the quantities present in our “standard” foods.

Typical results of feeding t,rials with these defective salt mixtures arc shown in a few appended charts. In several cases the out- come was quite unexpected to us. Thus the rats on the diets low in their content of magnesium (Chart II, Rats 3773, 3774), sodium (Chart I, Rats 3854, 3848), and chlorine (Chart III, Rats 4167, 3850) respectively, grew with vigor in so far as one may judge by gains in body weight. IAXS than 0.04 per cent of either sodium or chlorine in the food sufficed to permit these rats to complete their growth. Indeed, one of these animals (Rat 38543, Chart I) grew t,o unusual size. A similar result was obtained with the diet-s which contained only slightly more than 0.01 per cent of magnesium (Chart 11). Here, however, the relative difference between the control food and the magnesium-low food is not so great as was the case for the other elcmcnts just discussed. When all three of the elements, magnesium, sodium, and chlo- rinc, were offered in barely more than traces, good growth was likewise possible (Chart. I, Rats 4048, 4038). With only 0.03 per cent of pot,assium in the diet considerable growth was like- wise attained (Chart I, Rats 3787, 3801). although a limit to increment of weight seemed to bc imposed by the proportion afforded in t,hcse esperiments. TVhen both sodium and potassium

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Inorganic Elements in Nutrition

were simultaneously decreased in amount (Chart I, Rats 4163, 4171) growth ceased. The subsequent addition of sodium alone (Diet VII) at an early stage of growth caused only slight gain; but later, on substitution of potassium for sodium (Diet X), rapid recovery took place. After this, growth continued when sodium replaced potassium. The explanation may be that when both sodium and potassium are lacking, potassium is excreted; but when the diet contains enough sodium, potassium is tena- ciously retained in the body.

In striking contrast with the foregoing experiences indicating the possibility of growth despite low levels of intake of either sodium, potassium, magnesium, or chlorine are the results of feeding diets low in calcium or phosphorus. The growth curves of Rats 3820, 3849, 3760, 3785, in Chart II, exhibit the char- acteristic slowing of growth which is promptly altered by the introduction of calcium in inorganic form. Our experiments also confirm those previously made by others in showing that even large additions of magnesium cannot replace calcium (see Rats 4166, 4120, Period XV, Chart II).

The lack of sufficient phosphorus in the diet is likewise promptly exhibited in a cessation or restriction of growth. From his studies of American dietaries Sherman” has reached the con- clusion that present food habits are more likely to lead to a de- ficiency of phosphorus compounds than to a deficiency of protein in the diet. He regards it as not improbable that many cases of malnutrition are really due to an inadequate supply of phosphorus compounds. In our experiments where the protein furnished phosphorus, as in the case of casein, the inhibition of growth was not so pronounced as where the protein edestin, which contains no phosphorus, was furnished. With edestin foods, likewise, addition of inorganic phosphorus to the diet brought prompt responses (see Rats 4119, 4124, Chart III), thus proving that, aside from possible minute quantities, phosphorus in organic combination is not. needed by the growing animal.

It has long been known that the organism can endure a con- siderable reduction in the customary intake of sodium chloride without any obvious untoward effects. There seems to be an

6 Sherman, H. C., Chemistry of Food and Nutrition, New York, 1911, 265.

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T. B. Osborne and L. B. Mendel 137

extraordinary capacity for adjustment to varying quantities of this salt. When an abundance is offered in the diet the elimina- tion of chlorides through the kidneys, which are the only signi- ficant path for their excretion, is large; on a restricted chloride intake the output promptly falls (except perhaps in certain cases of pathologic “salt retention”). In starvation the output does not contiriue at a low level as is the case with some of the other inorganic elements and nitrogenous wastes, but sinks almost to zero. Referring to observations on man Sherman states that even where there was complete deprivation of salt during 10 to 13 days, the total loss did not exceed 10 to 15 per cent of the amount estimated as usually present in the body. Rosemann has demonstrated that a diet deficient in chlorides leads at most to an insignificant reduction of t,he total chlorine content. of the body in animals. Excretion of the element st.ops under such conditions; but signs of malnutrition are speedily elicited when chlorine is withdrawn from the body by actual ramoval of the hydrochloric acid of the gastric juice through a fistula. Until such losses are artificially enforced the gastric juice still maintains essentially its normal composition with respect, to hydrochloric acid. The abilit,y of our ra,ts to cont.inue in health for a time on a diet low. in chlorine might have been anticipated on the basis of previous experience. It could not, however, have been expected that they would continue to thrive so Iong or attain so many t,imes t,heir original weight on such an extremely low chlorine intake.” The outcome of these experiments cannot be due to substitution of other anions for chlorine, but is attributable to a husbanding of this specific element.

What applies to chIorine is presumably t,rue of some of the other elements like sodium, potassium, and magnesium. That these may t,o some degree be essential to the adjustments of neu- trality regulation is indicated by the faihrre to grow when both sodium and potassium were practically excluded from t,he diet, whereas growth was nearly or quite normal when only one of t,hese elements was missing. That these elements take part in the processes regulating the neutrality of the body fluids is to be assumed from what has been learned by experimental work in

’ Rosemann, R., Arch. ges. Physiol., 1011, cxlii, 208. 8 The nnimel body cont)sins about 0.2 per cent chlorine.

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138 Inorganic Elements in Nutrition

vitro along these lines, and also from the fact that our experi- ments with diets essentially free from both sodium and potassium have led to nutritive failure.

From our experiments with the so called “magnesium-free” diets, no conclusions can be drawn respecting either the persist- ency of its retention or the part it takes in regulating neutrality, because the amount of magnesium in the diets used was not relatively very low compared with the amount present in many ordinary foods.

That in the long run much smaIler quantities of those inorganic elements which can be husbanded will be required for well-being than of those which are needed for the maintenance of neutrality and hence are continuously eliminated is manifest, wholly apart from any quantity necessary for the construction of special tissues like bone or for t,he production of milk.

We believe that the conventional “salt balance” experiments are less likely to permit a satisfactory elucidation of the need and Ale of the specific inorganic elements than feeding experi- ments, of which beginnings are here reported; for in these every factor can be better controlled. Recent studies plainly show t.hat a deficiency of any factor essential for growth is followed by a fn.ilurc: of growth of the body a,s a whole, and not by the production of abnormal tissues due to the lack of some element. Here again the “law of minimum” reasserts itself in the part played by salts in nutrition.

Tllc fact that the growing animal can fully supply from inorganic SOLWXS its requirements for the elements specially discussed in this paper emphasizes anew that it is unnecessary to consider the prcscnce of ca~lcium, phosphorus, and iron, for example, in natural foods to the degree that is currently believed.g Any shortage of an essent.ial inorganic element can be suitably remedied under ordinary condiiions by the use of its salts. For feeding farm animals, where the lack of calcium and phosphorus in their grain rat,ions ‘is always encountered, the demonstration that complete nutrition can be attained upon diets in which the inorganic

g See Sherman, H. C., and Gillett, I,., The Adequacy and Economy in Some City Dietaries, Sew York, 1917.

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T, B. Osborne and L. B. Mendel 139

ingredients are supplied in the form of their commercial salts has a significance that is just beginning to be appreciated.lO

lo An excellent r&urn6 of the literature on the requirements of farm animals for mineral matter will be found in Henry, W. A., and Morrison, F. B., Feeds and Feeding, Madison, 15th edition; 1915, 62. See also numerous recent bulletins of the Ohio Agricultural Experiment Station by Forbes and collaborators.

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260

240

160

Experimental food Standard food

~

Character of Diets

CHART I!. Showing good growth on diets comparat.ively low in magnesium (Rats 3773 and 3774). When the diet was low in calcium (Period IX, Rats 3820, 3849, 3760, 3785) growth invariably stopped sooner or later and usually decline ensued until calcium was reintroduced into the diet in some form. 1vhere the “standard food” was employed the recovery was prompt and rapid (Period IV, Rats 3849, 3760, 3785). It will be noted that when restoration was brought, about by addition of calcium carbonate in the periods after the decline on diets poor in calcium (Period IX, Rats 3820, 3849, 3760, 4120, 3755) the response was usually more pronounced with a higher content of calcium (1.35 per cent C~COJ) than with the lower supplcmcnt, (0.35 per cent CaC&). Rats 4166 and 4120 which received during Period XV a diet poor in calcium failed to thrive despite a Inrgcly augmcntcd supply of magnesium. This is only another illustration of the now established fact that magnesium cannot replace calcium in the body. Period IV at, the cm1 of the feeding t,rials marks the return to the “standard food.” The complete composition of the foods is indicated in the test.

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460

440

420

400

r;rperlmental food starmara rot (solid line) (dotted line I

VII - 33 lug. x IV - 033 mg. x X - 36 mg. Na IV - 185 mg. Bc3. XIII =(33 me;- K 35 rrg. 18

Iv =(a33 mg. K 186 mg. lfa

36 mg. Ba 186 mg . Pla I XII -112 mg. Mg IV -1 80 W. Ma

35 ug. Cl 529 mg. Cl

380

360

341

320

300

260

Character of Diets

DdYS

CHART I. Showing excellent growth of albino rats on diets low in sodium (Rats 3854 and 3848), and on diets low in sodium, chlorine, and magnesium (Rats 4048 and 4038). Very considerable growth was also obtained on diets decidedly low in potassium (R.ats 3787 and 3801). In the case of Rats 4163 and 4171

no growth was obtained during the first period (XIII) in which the diet was low in both sodium and potassium. Growth was not satisfactory in these animals until

potassium had been introduced for a time (Period X) into the diet,. Period IV at the end of t.he feeding trials marks the return to the “standard food.” The

complete composition of the foods is indicated in the text.

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320' Character of Diets

340w XIB low in Cl XVI low in P

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Days CHART III. Showing excellent growth on diets low in chlorine (Rats 4167 and 3850, Period XIB) and the failure to grow on

diets poor in phosphorus (Rats 4124, 4119, Period XVI). It will be noted in the latter cases that the nutritive failure was far more rapid when the phosphorus-free protein edestin was fed than when the phospho-protein casein entered into the diet. In the Periods IV, edestin, Rat 4124, practically all of the phosphorus was supplied in inorganic form. Period IV at the end of the feed- ing i.rials marks the return to the “standard food.” The complete composition of the foods is indicated in the text.

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Alfred J. WakemanWith the cooperation of Edna L. Ferry and

Thomas B. Osborne, Lafayette B. Mendel andNUTRITION

THE INORGANIC ELEMENTS IN

1918, 34:131-139.J. Biol. Chem. 

  http://www.jbc.org/content/34/1/131.citation

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